Hike into Bear Canyon on the northeastern edge of Tucson, and you'll be rewarded (most of the year) with a view of Seven Falls, gushing out of the Santa Catalina Mountains.
Even though the hike in and out is around seven miles, it's mostly flat. You'll find that, as you're zigzagging across the creek on large boulders, with cliffs above the cacti all around, traffic and strip malls are a world away. When you arrive at the falls, the rushing waters are a balm for the soul.
Midwinter through the middle of spring is a good time to visit this oasis; the higher-elevation snowmelt guarantees flowing water and the daytime temperatures are comfortable. Midsummer monsoon rains can also fill this canyon, and flash floods can be a sudden danger.